Method and apparatus for transmitting data

ABSTRACT

Embodiments of the present disclosure provide a method for transmitting data, including: sensing, by a first device, a scheduling assignment (SA) of another device; measuring a received power of the other device, and measuring a total received energy of a subframe/subband; determining a received power reference value and a total received energy reference value of the other device according to the SA; selecting resources; and transmitting data using the selected resources. According to the method of the present disclosure, the performance of the method which avoids collision based on SA is improved, and measurement accuracy of the total received energy of the subband is increased. Thus, resource selection/re-selection can be performed better. As such, interferences between devices can be avoided effectively.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/320,824, filed on Jan. 25, 2019, which has issued as U.S. Pat.No. 11,032,849 on Jun. 8, 2021, which was a U.S. National Stageapplication under 35 U.S.C. § 371 of an International application numberPCT/KR2017/007910, filed on Jul. 21, 2017, which is based on and claimedpriority of a Chinese patent application numbers 201610597275.7, filedon Jul. 26, 2016, 201610652706.5, filed on Aug. 10, 2016,201610663604.3, filed on Aug. 12, 2016, and 201610843063.2, filed onSep. 22, 2016, in the State Intellectual Property Office of the People'sRepublic of China, the disclosures of which are incorporated herein byreference in its entirety.

BACKGROUND 1. Field

The present invention relates to wireless communications technologies,more particularly to a method and an apparatus for selecting orre-selecting resources to transmit data in a V2X system.

2. Description of Related Art

At present, Device To Device (D2D) communications technique has beenaccepted by 3GPP standards due to its huge potential benefits in publicsecurity field and common civil communications field, andstandardization of some functions has been finished in 3GPP Rel-12 andRel-13, including: D2D discovery for an in-coverage scenario, D2Dbroadcast communication for an In-Coverage (IC) scenario, a PartialCoverage (PC) scenario and an Out-of-Coverage (OC) scenario.

At present, 3GPP Rel-12 has defined two D2D broadcast communicationmodes, respectively Mode 1 and Mode 2. Mode 1 requires that abroadcasting UE of the D2D communication shall be an In-Coverage UE(ICUE). The UE obtains configuration information of a Physical SidelinkControl Channel (PSCCH) resource pool of Mode 1 through receiving systembroadcast signaling transmitted by eNB, including PSCCH periodicity andpositions of subframes for transmitting PSCCH in each period, andpositions of Physical Resource Blocks (PRBs) for transmitting the PSCCHin each subframe. If the UE supporting the Mode 1 broadcastcommunication has a data transmission requirement, the UE applies fordedicated Mode 1 communication resources from the eNB via a specificBuffer Status Report (BSR); then, the UE detects sidelink grant of theeNB before each PSCCH period, and obtains the positions of the resourcestransmitting the PSCCH and the Physical Sidelink Shared Channel (PSSCH)in the PSCCH period. In Mode 1, resource conflict between different UEsmay be avoided via centralized control of the eNB.

The broadcasting UE of a D2D communication in Mode 2 may be an ICUE, ormay be an Out-of-Coverage UE (OCUE). The ICUE obtains the PSCCH resourcepool and associated PSSCH resource pool configuration of Mode 2 throughreceiving eNB system broadcast signaling, wherein the PSSCH resourcepool includes positions of subframes used for transmitting the PSSCH inan associated PSCCH period and the positions of the PRBs used fortransmitting the PSSCH in each subframe. In each PSCCH, resources fortransmitting the PSCCH and the associated PSSCH are selected randomly.The OCUE determines the PSCCH resource pool and the associated PSSCHresource pool configuration according to pre-configured information. Theresource selection manner is similar to that of the ICUE. In a PCscenario, the Mode 2 resource pool configuration pre-configured by theOCUE is relevant to the carrier-frequency, system bandwidth and/or TDDconfiguration of a cell where the ICUE participating in the D2Dbroadcast communication belongs to.

In the above two D2D broadcast communication modes, the PSCCH resourcepool and the PSSCH resource pool or the PSSCH resource are bound one byone. In each PSCCH period, the position of the PSCCH resource pool isahead of the associated PSSCH resource pool or PSCCH resource, and theresources of them do not overlap. In addition, all D2D terminals operatein half-duplex mode, which results in that terminals transmittingsignals simultaneously cannot receive the signals of the other side. InRel-12, in each PSCCH period, each PSCCH is transmitted for two times,each time of PSCCH transmission occupies one PRB, and the abovehalf-duplex problem is solved via resource hopping. For example, for thePSCCHs which are transmitted in the same subframe at the first time, anoffset is generated for the positions of the subframes for the secondtime transmission. The offset is relevant to the frequency position ofthe transmission resource of the first time, so as to ensure that thepositions of the subframes used for retransmission of the PSCCHs whichare transmitted in the same subframe in the first time are different. Inaddition, the two times of transmission also ensures receivingreliability of the PSCCH.

FIG. 1 shows an uplink subframe structure of a D2D system defined by3GPP. In the 14 OFDM symbols of a subframe, two OFDM symbols, withsymbol indexes of respectively 3 and 10, are used for transmittingDemodulation Reference Signal (DMRS). The last OFDM symbol in thesubframe is punctured fixedly for providing a transmitting/receivingswitching time and avoiding overlap of two adjacent subframes due toreasons such as propagation delay, timing advance, etc. Other symbolsare used for transmitting uplink data. Herein, the first OFDM symbol ofthe subframe is also used for transmitting data. In practicalapplications, this OFDM symbol may also be used for Automatic GainControl (AGC).

The D2D communication proposed by 3GPP is mainly designed for low speedterminals and V2X services which are not delay sensitive and have lowreceiving reliable requirement. Therefore, the existing D2D capabilitiesare far from meeting the user's requirements. In subsequent 3GPPreleases, various communications terminal vendors and communicationsnetwork device vendors have reached a consensus to improve the D2Dfunctional architecture. Based on the current D2D broadcastingcommunication mechanism, one of functions need to be standardizedfirstly is to support direct low latency and high reliabilitycommunications between high speed devices, high speed device and lowspeed device, and high speed device and fixed device, i.e., Vehicle ToVehicle, Pedestrian/Infrastructure/Network (V2X).

The uplink subframe structure as shown in FIG. 1 meets the mostapplication scenario requirements of D2D. However, as to a typical V2Xapplication scenario, e.g., V2X communication requires that a relativemoving speed of up to 500 km/h of UE is supported, the carrier frequencymay reach 6 GHz, the Doppler frequency shift brought out by the highmoving speed and the high carrier frequency may lead to seriousinter-carrier interference, in addition, considering the impact of thedifference timing offset and frequency offset between the base stationand the UE, the DMRS pattern as shown in FIG. 1 cannot meet performancerequirement. In current discussion of 3GPP meetings, the solution asshown in FIG. 2 is an important solution, i.e. through transmitting DMRSon 4 OFDM symbols, the time density of the DMRS is increased, i.e., theindexes of the DMRS symbols are 2, 5, 8 and 11, so as to provide betterperformance.

In the D2D system proposed by 3GPP, the DMRS sequence of PSCCH is fixed,i.e. all transmitting ends use the same DMRS sequence. In particular,based on the DMRS generating method of LTE, a DMRS root sequence isobtained according to a Physical Cell ID (PCID) 510, and the CyclicShift (CS) of the DMRS is fixedly to be 0, the Orthogonal Cover Code(OCC) is [1 1]. The scramble sequence of the scheduling informationcarried by the PSCCH is also fixed, i.e., all of the transmitting endsuse the same scramble sequence. In particular, based on the scramblegeneration method of LTE, PCID is configured to 510, other informationsuch as slot index and UE identifier is configured to 0 fixedly. Base onthis method, if two devices transmit SA on the same PRB, the DMRS of thetwo devices are overlapped completely, equivalent as one DMRS sequenceat the receiving end. Since the terminal density in the V2Xcommunication is far higher than D2D, the probability that two or moredevices transmit SA and/or data on the same resource is dramaticallyincreased, i.e. the SA resource conflict is dramatically increased. Inaddition, besides the conflict, even if two transmitting devicestransmit data on different frequencies of the same subframe, consideringthe impact of near-far effect, the in-band leakage interference alsoseriously affect the receiving performance. In other words, for areceiving end, the energy leaked to an adjacent PRB by a near device mayhave similar or even higher amplitude than the signals on the adjacentPRB from a remote device. Since the terminal density in the V2X is farhigher than D2D, the above in-band leakage interference may become moreserious.

According to the discussion of current standardization meetings, onesolution is to solve the collision and in-band leakage via sensing.Herein, a basic assumption is that devices occupy resources in aSemi-Persistent (SPS) manner, i.e., a device occupies resourcesperiodically during a period of time. As shown in FIG. 3, suppose that adevice selects the PSCCH/PSSCH resource in subframe n, the devicefirstly senses the resources in the resource pool in the time periodfrom subframe n-a to subframe n-b, and determines which time-frequencyresources are occupied and which time-frequency resources are idle; andthen selects the PSCCH/PSSCH resource in subframe n, suppose thatsubframe n+c is selected for transmitting PSCCH, subframe n+d isselected for transmitting PSSCH, and resources in subframe n+e arereserved. Then, PSCCH is transmitted in subframe n+c, and PSSCH istransmitted in subframe n+d, and a next data is transmitted on reservedresources in subframe n+c. The device may sense the resources in theresource pool via two manners. One is to obtain accurate channeloccupation information of other devices via decoding the PSCCH, so as tomeasure the received power of the corresponding devices. The other isbased on measurement of the energy of the PSSCH resource pool. Theformer manner may obtain accurate channel occupation and reservationinformation. However, if the PSCCH is not correctly received, e.g.PSCCHs of several devices collides, the sensing based on PSCCH fails.The later method is to determine whether resources are occupied based onamplitude of the measured energy, so as to avoid using occupiedresources as much as possible. However, since the V2X service is notstrictly periodic, messages of different devices in a period of time mayhave different periodicities, which affect the prediction performance ofthe energy measurement method. Actually, the PSCCH-based sensing and theenergy-based measurement may be utilized in combination to avoidcollision and interference as much as possible and improve performance.In the case that PSCCH is correctly received, it is problem to be solvedthat how to measure the energy of the PSCCH.

Technical Solution

Embodiments of the present disclosure provide a data transmittingmethod, a device and a base station, and provide a method.

In view of the above, embodiments of the present disclosure provide thefollowing solution.

According to an embodiment of the disclosure, a data transmitting methodincludes:

sensing, by a first device, a scheduling assignment (SA) of anotherdevice;

measuring a received power of the other device, and measuring a totalreceived energy of a subframe/subband;

determining a received power reference value and a total received energyreference value of the other device according to the SA;

selecting resources; and

transmitting data using the selected resources.

In some embodiments, the resources are selected in subframe n, if asubframe/subband after subframe n is occupied for data transmission byat least one device and if the received power reference value of the atleast one device on the subframe/subband exceeds a threshold Th.

In some embodiments, a data transmitting method includes obtaining a sumof received power reference values of at least one other device; and

comparing the sum of the received power reference values with athreshold Th2,

wherein the resources are selected in subframe n, if thesubframe/subband after subframe n is occupied for data transmission byat least one device and if the sum exceeds the threshold Th2.

In some embodiments, a data transmitting method includes dividing atleast one other device into at least one group;

obtaining a sum of received power reference values of the at least onegroup; and

comparing the sum with a threshold Th3,

wherein the resources are selected in subframe n, if thesubframe/subband after subframe n is occupied for data transmission bythe at least one other device, if the sum exceeds the threshold Th3.

In some embodiments, the dividing is performed based on:

one or more parameters of the K devices;

or, configuring an independent threshold Th for each of the K devices.

In some embodiments, the threshold is a common value for differentdevices; or

the threshold is determined according to one or more parameters of thefirst device; or

the threshold is determined based on one or more parameters of theanother device; or

the threshold is determined according to a combination of one or moreparameters of the first device and one or more parameters of the anotherdevice.

In some embodiments, if the resources are selected in subframe n, for asubframe m occupied by the first device in a sensing window, allsubframes z=mP_(q) after subframe n are unusable for the first device,wherein P_(q) denotes a resource reservation periodicity, q∈Q, Q issemi-statically configured by higher layer or predefined; R_(x,y)denotes a single subframe resource in a selection window, y is an indexof a subframe where R_(x,y) is located, x is an index of a subband wherestarts; if there is a value j which makes y+j·P_(A)=z, R_(x,y) isunusable for the first device, j is an integer larger than or equal to0, or j is an integer larger than or equal to 0 but smaller than C, Cdenotes a number of periods that the first device performs resourcereservation according to a periodicity P_(A);

or, if the resources are selected in subframe n, for the subframe moccupied by the first device in the sensing window, all subframesz=m+k×P₀ after subframe n are unusable for the first device, k is apositive integer or an integer larger than or equal to 1 but smallerthan max(P_(q))/P₀; if there is a value k which makes z located in aselection window, all single subframe resources in subframe z in theselection window are unusable for the first device.

In some embodiments, the subframe m occupied by the first device in thesensing window is one of subframes where resources occupied by the firstdevice obtained by a last time resource re-selection in the sensingwindow or all subframes occupied by the first device in the sensingwindow.

In some embodiments, the subframe m occupied by the first device in thesensing window is one of a subframe in which the SA and data aretransmitted, a subframe in which data is transmitted, a subframe inwhich data is transmitted or subframes in which SA is transmitted inlast X periods, wherein the X is a predefined constant or a valueconfigured by higher layer signaling.

In some embodiments, if a second device occupies resource Y aftersubframe n, wherein the received power reference value on resource Y isP_(RSRP) ^(PSSCH), R_(x,y) denotes a single subframe resource in aselection window, y is an index of the subframe that R_(x,y) is located,and x denotes an index of the subband where R_(x,y) is started,

if R_(x,y+j·P) _(A) overlaps with the resource Y, obtaining P_(RSRP)^(PSSCH,(e)) according to P_(RSRP) ^(PSSCH), if P_(RSRP) ^(PSSCH,(e))exceeds the threshold, R_(x,y) is unusable for the first device, j is aninteger larger than or equal to 0 or an integer larger than or equal to0 but smaller than C, C is the number of periods that the first deviceperforms resource reservation according to periodicity P_(A);

wherein the obtaining P_(RSRP) ^(PSSCH,(e)) according to P_(RSRP)^(PSSCH) comprises:

P_(RSRP) ^(PSSCH,(e))=P_(RSRP) ^(PSSCH)·L/N, wherein N denotes thenumber of subbands of R_(x,y+j·P) _(A) , R_(x,y+j·P) _(A) overlaps withthe resource Y on L subbands; or

P_(RSRP) ^(PSSCH,(e))=P_(RSRP) ^(PSSCH)·L′/N′, wherein N′ denotes thenumber of PRBs of R_(x,y+j·P) _(A) , R_(x,y+j·P) _(A) overlaps with theresource Y on L′ PRBs.

In some embodiments, wherein the determining the total received energyreference value of the other device comprises:

if the resources are selected in subframe n, removing impact of receivedpower on released resources, and determining the total received energyreference value of subbands of a subframe after subframe n.

In some embodiments, the determining the total received energy referencevalue of the another device comprises:

receiving, data in the subframe/subband in a sensing window withoutoccupying the subframe/subband after subframe n with the other device,if the selecting resources is performed in subframe n and the totalreceived energy of the subframe/subband in the sensing window is usedfor determining the received energy reference value of asubframe/subband after subframe n;

removing an impact of the received power of the other device, measuringthe total received energy of the subframe/subband in the sensing window;or

removing the impact of the received power of the other device to obtainthe total received energy reference value of the subframe/subband aftersubframe n.

In some embodiments, the determining the total received energy referencevalue of the another device comprises: receiving, data in thesubframe/subband in a sensing window without occupying thesubframe/subband after subframe n with the another device, if theresources are selected in subframe n and the total received energy ofthe subframe/subband in the sensing window is used for determining thereceived energy reference value of a subframe/subband after subframe n,the subframe/subband after subframe n is occupied with the other devicewhich does not transmit data in subframe/subband of the sensing window;

adding an impact of the received power of the other device and measuringthe total received energy of the subframe/subband in the sensing window;or

adding the impact of the received power of the other device, to obtainthe total received energy reference value of the subframe/subband aftersubframe n.

In some embodiments, the determining the total received energy referencevalue of the other device comprises:

for a subframe/subband in the sensing window, removing signals of a datachannel scheduled by a correctly received SA, measuring the totalreceived energy of all remaining signals on the subframe/subband;

determining the total received energy reference value of the remainingsignals of a subframe/subband after subframe n according to the totalreceived energy of the remaining signals on the subframe/subband in thesensing window, wherein the selecting resource is performed in subframen;

for the subframe/subband after subframe n, determining according to areceived SA a received power reference value of a device transmittingthe SA on the subframe/subband, and obtaining the total received energyreference value according to the total received energy reference valueof the remaining signals and the received power reference value.

In some embodiments, the removing the signals of the data channelscheduled by the correctly received SA comprises:

removing the signals of the data channels scheduled by all correctlyreceived SAs; or

if a received power of a data channel scheduled by the SA exceeds athreshold, removing the signals of the data channel scheduled by the SA.

According to an embodiment of the disclosure, a device for datatransmission, comprising:

a sensor; a transmitter/receiver; and

a processor configured to control the sensor to sense a schedulingassignment (SA) of another device and measure a received power of theother device, and measure a total received energy of a subframe/subband;determine a received power reference value and a total received energyreference value of the other device according to the SA and selectresources; and

control the transmitter/receiver to transmit data the selectedresources.

According to the method provided by the present disclosure, theperformance of the method which avoids collision based on SA isimproved, and measurement accuracy of the total received energy of thesubband is increased. Thus, resource selection/re-selection can beperformed better. As such, interferences between devices can be avoidedeffectively.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating an uplink subframe of anexisting LTE system.

FIG. 2 is a schematic diagram illustrating an uplink subframe in whichDMRS is transmitted on 4 OFDM symbols.

FIG. 3 is a schematic diagram illustrating a sensing-based channelresource selecting/re-selecting procedure.

FIG. 4 is a flowchart illustrating a method of sensing channel andselecting/re-selecting channel resources according to some embodimentsof the present disclosure.

FIG. 5 is a schematic diagram illustrating data channel occupation oftwo devices in the case that the periodicity of one device is a multipleof the other.

FIG. 6 is a schematic diagram illustrating data channel occupation oftwo devices in the case that the periodicity of one device is not amultiple of the other.

FIG. 7 is schematic diagram illustrating release of resources.

FIG. 8 is a schematic diagram illustrating a situation that the devicedoes not occupy a subframe/subband after subframe n.

FIG. 9 is a schematic diagram illustrating a situation that the deviceoccupies a subframe/subband after subframe n.

FIG. 10 is a schematic diagram illustrating measurement of receivedenergy of remaining signals.

FIG. 11 is a schematic diagram illustrating a structure of a deviceaccording to some embodiments of the present disclosure.

FIG. 12 is a schematic diagram illustrating candidate resources in aselection window according to some embodiments of the presentdisclosure.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail hereinafter withreference to accompanying drawings and embodiments to make the technicalsolution and merits therein clearer.

In V2X communications, there may be a lot of devices within a certainarea, including vehicles, pedestrians and Road Side Units (RSUs), andthey may all have data transmission requirements, which may lead to ahigh probability of collision and interferences when the devicestransmit data.

For one device, since its data is generated periodically, the deviceneeds to occupy resources periodically. In addition, each data may beretransmitted for K times, K is larger than or equal to 1, so as toavoid that the data cannot be received by other devices due to therestriction of half-duplex mode. Accordingly, the device occupiesresources with a periodicity of P, and occupies K subframes within oneperiod. In other words, K resources are allocated to the device, andeach resource is allocated periodically with a periodicity of P. For onedevice, after selecting certain resources and occupying the resourcesfor several periods, the device releases the resources and performsresource selection again. This is to avoid continuous collision if anadjacent device selects the same resources. During each time of resourceselection/re-selection, it is possible to randomly generate, within therange [P_(min), P_(max)], a periodicity C during which the sameresources may be continuously occupied, and then select the resourcesthat can be continuously occupied during the C periods, wherein P_(min)and P_(max) are pre-defined constants or pre-configured values, e.g.,respectively 5 and 15. Then, subtract 1 from a resource re-selectioncounter after each time of data transmission. When the value of theresource re-selection counter is returned to zero, the resourcere-selection is performed.

Suppose that a data transmission mechanism of the device is as follows:firstly, the device transmits a control channel, hereinafter referred toas Scheduling Assignment (SA), for indicating information such astime-frequency resources occupied by a data channel and modulation andcoding scheme (MCS) of the data channel; then, the device transmits dataon the scheduled data channel For a LTE D2D/V2X system, the above SA isalso referred to as PSCCH and the data channel is also referred to asPSSCH. As to the information carried by the SA, the SA may includeindication information indicating whether the device continues to occupythe currently allocated subframe/subband in one or more subsequentperiods (hereinafter, subframe/subband can mean subframe and subband).The above subframe/subband refers to one subband in one subframe and isa unit for resource allocation. One subband may include one or morecontinuous PRBs. The data channel of one device may occupy one or moresubbands in one subframe. If there is no such indication information,device A may fixedly regard that device B continuously occupy thecurrently allocated subframe/subband in the next period. This manner mayavoid possible collision. But if the device B releases the resources inthe next subframe, the resources cannot be effectively utilized forresource selection/re-selection. Alternatively, device A may record thenumber of periods that device B occupies the same resources. Ifdetecting that device B has continuously occupied the resources forP_(max) times, device A may regard that device B has released theresources. Generally, if device A receives the SA of device B and theresources allocated by the SA are not released after subframe n, deviceA regards that device B continues to occupy the resources after subframen.

According to the resource selection/re-selection mechanism as shown inFIG. 3, assume that device A performs resource selection/re-selection insubframe n, and is able to determine the resource occupation situationafter subframe n according to a sensing result in subframes [n-a, n-b],hereinafter referred to as a sensing window, so as to select/re-selectappropriate resources for SA and the data channel Within the sensingwindow, device B generally transmits data in multiple periods andtransmits the same data for multiple times within one period.Accordingly, device A performs multiple measurements to device B. Forone measurement, an average of received powers on all subbands occupiedby device B may be obtained; or, a received power on each subbandoccupied by device B may be obtained. For example, the received powermay be the received power on one subband, or the received power on onePRB, or the received power on one subcarrier.

In order to avoid collision and reduce interferences between devices asmuch as possible, some embodiments of the present disclosure provide amethod as shown in FIG. 4.

In step 401, device A senses an SA of another device, and measures areceived power of a data channel scheduled by a correctly received SA,and measures received energy of each subband in each subframe.

After decoding an SA and obtaining information of the SA, device A mayobtain accurate information about the channel occupied by the devicetransmitting the SA. For a successfully decoded SA, received power ofthe SA of the device transmitting the SA may be further measured, so asto assist the resource selection/re-selection. The received power of theSA may be measured. Since the transmission powers of the SA and the datachannel transmitted by the same transmitting device are not independent,e.g., in the case that the received power of the SA is high, thereceived power of the data channel is generally also high, the receivedpower of the SA is able to reflect the received power of the datachannel of the device transmitting the SA. Or, it is also possible tomeasure the received power of the data channel scheduled by the SA,e.g., the received power of DMRS.

Another kind of information may be used for assisting the resourceselection/re-selection is a total received energy of eachsubframe/subband in a resource pool. The total received energy refers tothe total received energy on one subband, i.e., if multiple transmittingdevices transmit signals on one subband, the above energy refers to thetotal energy of combined signals of the multiple transmitting devices.If device A does not receive the SA, the above energy may still be usedfor assisting the resource selecting/re-selection. However, due to lackof necessary information about future resource occupation, theperformance of device A during resource selection/re-selection isaffected.

In step 402, device A determines a received power reference value of theother device and a total received energy reference value according tothe received power of the other device and the total received energy ofeach subframe/subband, and selects resources according to the receivedpower reference value and the total received energy reference value.

Suppose that the SA includes an identifier of device B. Thus, it ispossible to recognize the resources occupied by device B in multipleperiods according to the identifier. These resources may be used forobtaining the received power reference value of device B. Otherwise,suppose that the SA does not include the identifier of device B. If theSA indicates resources for initial transmission and re-transmission ofone data, after receiving the SA, device A merely knows that resourcesoccupied by the data for initial transmission and retransmissionscheduled by the SA are from the same device B. As such, it is merelyable to obtain the received power when device B transmits the dataaccording to the initial transmission and re-transmission resources.

For device B, in some cases, device A may miss an SA of device B due tosome reasons, e.g., SA decoding error due to collision, or, device A isperforming a transmission operation when device B transmits the SA andtherefore cannot receive the SA. In the sensing window [n-a, n-b], forone of the K resources corresponding to device B, assume that device Adoes not receive the SA in one period, device A may still able toprocess the resource in this period according to other SAs of the deviceB and measure the received power on this resource. Assume that device Amisses the last one or more SAs before the sensing window ends, device Amay still able to determine the resource occupation situation of deviceB after subframe n according to other SAs of device B.

For device B, in some cases, device A may miss the data channel on oneresource of device B for some reasons, e.g., SA decoding error due tocollision, or, device A is performing a transmission operation whendevice B transmits the data channel and therefore cannot receive thedata channel In addition, according to the resourceselection/re-selection mechanism as shown in FIG. 3, assume that deviceA successfully receives the SA of device B at a position close to theend of the sensing window [n-a, n-b], e.g. the subframe close tosubframe n-b, but the data channel scheduled by this SA is later thansubframe n-b, i.e., device A has not receive the data channeltransmission yet in the sensing window or has no enough time to processthe data channel transmission, and thus cannot measure the receivedpower of the data channel of device B. In one period, assume device Adoes not receive the data channel of device B on one resource. At thistime, device A is able to estimate the received power on this resourceof the current period according to the measurement of other signals. Forexample, the received power in this period may be obtained based on thereceived power of device B on this resource in other periods; or, thereceived power of device B on the resource may be obtained based on thereceived power on other resources; or, the received power of device Bmay be obtained according to the measurement of SA of device B. As tothe method based on the measurement of SA, it is possible to measure thereceived power based on the SA only when the SINR of the current SA isrelatively high, so as to ensure measurement accuracy. Device A mayconfigure the received power of device B on this resource to a value,e.g., a large value, such that the resource of device B is unavailablefor device A after subframe n. Therefore, it is not required to considerthe received power on this resource in the current period. Inparticular, if device A does not receive any data transmission of deviceB within the sensing window, the method for measuring received powerbased on the SA may be adopted, or the method that directly configuringthe received power to a large value may be adopted.

In the sensing window, as to the subframes in which device A transmitsSA and/or data channel, due to the restriction of the half-duplex mode,device A cannot measure the received power of other devices or measurethe total received energy, i.e. device A misses the measurement of otherdevices in these subframes. When device A performs resourceselection/re-selection in subframe n, in order to avoid impact to otherdevices transmitting data in the subframe occupied by device A in thesensing window, it is required to process the subframes occupied bydevice A. For the situation that the SA of one device and the datachannel scheduled by the SA are located in the same subframe, in thesubframe occupied by device A, device A misses both the SA and the datatransmission of the other device. Device A processes the subframeoccupied by device A when dealing with resource reservation aftersubframe n. Assume that the SA of one device and the data channelscheduled by the SA are in different subframes, if device A merelymisses the SA or the data transmission of the other device, according tothe above method, device A may still be able to measure the receivedpower of this device. In this situation, device A does not need toperform additional processing to the subframe occupied by itself; or,considering that device A may also miss both the SA and the datatransmission of the other device, device A may also process the subframeoccupied by itself when dealing with the resource reservation aftersubframe n.

In a first method for processing the subframe occupied by device A, fora subframe m occupied by device A in the sensing window, subframescorresponding to subframe m after subframe n are reserved for allpossible periodicities P_(q), P_(q)∈Q, the reserved subframes are notused for transmission of device A. In other words, all subframesm+k×P_(q), P_(q)∈Q after subframe n cannot be used for the transmissionof device A. Assume that all of the possible periodicities are times ofa minimum periodicity P₀, e.g., P₀=100 ms, all subframes m+k×P₀ aftersubframe n cannot be used for the transmission of device A, k is aninteger larger than or equal to 1. Herein, suppose that device A needsto select resources and occupy C periods after subframe n. Therefore,subframes meeting m+k×P₀ in C periods after subframe n are not used fortransmission of device A.

In a second method for processing the subframe occupied by device A, fora subframe m in the sensing window occupied by device A, subframescorresponding to subframe m after subframe n may be reserved for someperiods having high missing probability. Assume the minimum periodicityis P₀ the interval between subframe m and the end position n-b of thesensing window is M=└(n−b−m)/P₀┘ minimum periodicities. Assume that theperiodicity of other device is smaller than or equal to M×P₀, the otherdevice still has at least one transmission chance in the sensing window.Device A may be able to detect the transmission of the other deviceaccording to the last transmission, such that the impact to theperiodicity which is smaller than or equal to M×P₀ may be notconsidered. It is possible to configure that all subframes m+k×P_(q)after subframe n cannot be used for transmission of device A, P_(q) islarger than M×P₀, k is an integer larger than or equal to 1. Similarly,assume that device A needs to select resources and occupy C periodsafter subframe n, therefore all subframes meeting m+k×P_(q) in C periodsafter subframe n cannot be used for transmission of device A, whereinP_(q) is larger than M×P₀.

In a third method for processing the subframe occupied by device A, fora subframe m in the sensing window occupied by device A, subframescorresponding to subframe m after subframe n may be reserved accordingto the periodicity of device A. Assume that the periodicity of device Ais P, thus all subframes m+k×P after subframe n cannot be used fortransmission of device A. Herein, assume that device A needs to selectresources and occupy C periods after subframe n, therefore all subframesmeeting m+k×P in C periods after subframe n cannot be used fortransmission of device A.

When selecting/re-selecting resources in subframe n, device A selectsthe resources in a selecting window. The values of and depend on theimplementation of UE. For example, [n+T₁, n+T₂]. The values of T₁ and T₂depend on the implementation of UE. For example, T₁≤4 and 20≤T₂≤100. Thevalue of T₁ depends on the processing delay of the UE from selectingresources to starting to transmit SA and data. The value of T₂ dependson the delay tolerance characteristic of the current service.

In a fourth method for processing the subframe occupied by device A,assume the SA merely indicates whether the resource is released orcontinuously occupied in a next period. For a subframe m occupied bydevice A in the sensing window, all subframes z=m+P_(q) after subframe nare not used for transmission of device A, wherein P_(q) denotesperiodicity of resource reservation, P_(q)∈Q. The set Q of theperiodicities may be semi-statically configured by higher layer; or theset Q of the periodicities may include merely one element, e.g., aminimum periodicity P₀ or resource reservation periodicity P_(A) whendevice A currently performing resource re-selection. The resource of asingle subframe within the selection window [n+T₁, n+T₂] is denoted byR_(x,y), i.e., R_(x,y) is subframe y and includes one or more continuoussubbands starting from subband x. If there is a value j which makesy+j·P_(A)=z, R_(x,y) is not usable for device, j may be an integerlarger than or equal to 0, or j is an integer larger than or equal to 0and smaller than C, C is the number of periods that device A needs toreserve resources according to the periodicity A.

In a fifth method for processing subframe occupied by device A, assumethat SA merely indicates whether the resource is released orcontinuously occupied in the next period. For a subframe m occupied bydevice A in the detection window, assume that all possible periodicitiesare multiples of a minimum periodicity P₀, e.g., P₀=100 ms. Thus, allsubframes z=m+k×P₀ after subframe n are not usable for device A, whereink is any integer, or k is an integer larger than or equal to 1 andsmaller than max(P_(q))/P₀. Assume that there is a value k which makesz=m+k×P₀ located within the selection window [n+T₁, n+T₂], all singlesubframe resources in subframe z in the selection window are not usablefor device A.

In the sensing window, device A generally transmits in multiplesubframes. Device A may occupy some resources and release theseresources in the sensing window, and device A re-selects and occupiesother resources. According to the above method, it is possible toprocess the subframes within the sensing window occupied by device Aafter the last resource re-selection, or process all of the subframesoccupied by device in the sensing window.

According to the above method, it is possible to process the subframeused for transmitting SA and the subframe used for transmitting dataoccupied by device A in the sensing window. Or, if the SA of one deviceand the data channel scheduled by the SA are in different subframes,since the SA may be transmitted in any subframe, the situation that thedevice cannot receive the transmission of other devices due to thetransmission of the SA is occasional and may not happen repeatedly, itis possible to process the resource reservation after subframe n merelyfor the subframes in which device A transmits data in the sensingwindow. Or, if the SA of one device and the data channel scheduled bythe SA are in different subframes, besides processing resourcereservation after subframe n for the subframes in which device Atransmits data in the sensing window, resource reservation aftersubframe n is merely performed for the subframes in which SA istransmitted in the last X periodicities in the sensing window, wherein Xis a predefined constant or a value configured by higher layersignaling, e.g., X=1.

Assume that device A performs resource selection/re-selection insubframe n. For device B, assume that device A correctly decodes the SAof device B and the resources allocated for the SA are not releasedafter subframe n. Thus, it is possible to determine a received powerreference value of device B after subframe n according to a receivedpower measurement value of device B in the sensing window. Specifically,assume that the SA does not include the identifier of device B. If theSA indicates the initial transmission resources and the retransmissionresources corresponding to one data, it is merely possible to obtain thereceived power reference value of device B after subframe n according tothe received power measurement value on the initial resources and theretransmission resources scheduled by the SA. The method for obtainingthe received power reference value based on the received powermeasurement value is not restricted in the present disclosure. Then,according to the SAs of various devices received in the sensing window,it may be determined whether the resource after subframe n is availablefor the transmission of device A according to scheduling information ofthe SAs and the received power reference values of correspondingdevices.

In addition, device A may determine the resource occupation situationafter subframe n according to some known or configured resourceoccupation periodicity information. Through determining a receivedenergy reference value of one subframe/subband after subframe naccording to a received energy measurement value on each subband in theresource pool in the sensing window, interference may be avoided as muchas possible. For example, for a subband in subframe y after subframe n,the received energy reference value may be obtained according to thereceived energy measurement value of the same subband in subframesy−k×P_(A) in the sensing window, or may be obtained according to thereceived energy measurement value of the same subband in subframey−k×P_(A) before the end of the sensing window, wherein k is a positiveinteger. For a subframe, if device A occupies this subframe fortransmission and thus does not measure the received energy, thissubframe is not used for calculating the received energy referencevalue. The received energy reference value may be an average value, aweighted average value or a moving average value of received energymeasurement values of the above subframes. For the V2X system, thedevice participating in the communication may move rapidly. For example,for two devices move with a relative velocity of 180 km/h, theirrelative position varies 50 m within one second, which may lead to alarge variance of the received energy. That is, due to the high movingspeed, the received energy measurement value adjacent to subframe nreflects the current situation more accurately. Therefore, for theweighted average operation and moving average operation, the weight ofthe received energy measurement value of the subframe adjacent tosubframe n is relatively large. The method for obtaining the receivedenergy reference value based on the received energy measurement value isnot restricted in examples of the present disclosure.

Embodiment 1

Device A senses an SA of another device in the sensing window. Accordingto the correctly received SA, if the resource allocated by the SA is notreleased after subframe n, device A may obtain the resource occupationsituation of said another device after subframe n. Herein, if device Adoes not sense one or more SAs of device B, device A may still be ableto determine the resource occupation situation of device B aftersubframe n according to other received SAs of device B.

According to the SA successfully received by device A in the sensingwindow, for one subframe/subband after subframe n, there may be one ormore devices need to transmit data in this subframe/subband. Forexample, in the sensing window, device A may successfully decodemultiple SAs, the data channels scheduled by them are in the samesubframe, and the subbands are completely the same or partially thesame. Assume that the resources allocated by the SAs are not releasedafter subframe n, the data channels of the multiple devices may stilloccupy the same subframes/subbands after subframe n. The resourceoccupation periodicities of the devices may be the same, and they occupythe same subframes/subbands in continuous periods after subframe n; or,their periodicities may be multiples of each other or not, they merelyoccupy the same subframes/subbands in some particular periods aftersubframe n. As shown in FIG. 5, assume that device 1 has a periodicityof 200 ms and occupies resources 511 and 512; whereas the device 2 has aperiodicity of 100 ms and occupies resources 501˜505, wherein resources511 and 502 overlap with each other, and resources 512 and 504 overlapwith each other. After subframe n, some transmissions (513 and 506)still occupy the same subframes. In fact, since the time that differentdevices starts the data transmission may be different, in the sensingwindow, device A may successfully decodes multiple SAs, wherein subbandsscheduled by the SAs are completely or partially the same, but the datachannels scheduled by the SAs are in different subframes. However, theSAs may still occupy the same subframe/subband after subframe n. Asshown in FIG. 6, device 1 has a periodicity of 500 ms and occupiesresources 611 and 612; whereas device 2 has a periodicity of 200 ms andoccupies resources 601˜604. Thus, after subframe n, some transmissions(613 and 605) may still occupy the same subframe.

For a subframe/subband, if there is merely one device B needs to occupythe subframe/subband for data transmission, the received power referencevalue of device B in this subframe/subband may be compared with athreshold Th, if the received power reference value exceeds thethreshold Th, the subframe/subband is not usable for device A. Thethreshold Th may be predefined or configured by higher layer.

For a subframe/subband, if there are K devices need to occupy thesubframe/subband for data transmission, the received power referencevalue of each of the K devices in the subframe/subband may be comparedwith a corresponding threshold Th, the threshold Th may be different orthe same for different devices. If the received power reference value ofat least one of the devices in the subframe/subband exceeds itsthreshold Th, the subframe/subband is not usable for device A.

In the above method, the value of Th may depend on one or moreparameters of device A. For example, the value of Th may be relevant tothe moving speed of device A. For example, the faster the moving speed,the faster the received power varies. A relatively small Th may be usedto avoid collision as much as possible. Or, the value of Th may berelevant to the service priority of device A. For example, for a servicewith a high priority, in order to obtain more available resources andensure the transmission performance of the high priority service ofdevice A, a relatively large Th may be adopted; or, from the perspectiveof view of avoid collision, a relatively small Th may be adopted. Or,the value of Th may be relevant to the service type of device A. Forexample, for a periodically transmitted service, since the interferencemay emerge repeatedly in multiple periods, a relatively small Th may beadopted, so as to avoid collision as much as possible. For anevent-triggered service, since the interference is a one-time event anddoes not last for a long time, a relatively large Th may be adopted. Or,the value of Th may be relevant to the transmission power of device A,the higher the transmission power, the larger the interference to otherdevices. Through configuring a relatively small Th, the collision may bereduced.

Alternatively, the value of Th may depend on one or more parameters ofdevice B, such that the value of Th may be different when device Aprocesses with respect to different devices B. For example, the value ofTh may be relevant to the moving speed of device B. For example, thefaster the moving speed, the faster the received power varies. Arelatively small Th may be adopted to reduce collision as much aspossible. Or, the value of Th may be relevant to the service priority ofdevice B. For example, for a service with a high priority, in order toavoid collision better and improve the transmission performance ofdevice B, a relatively small Th may be adopted. Or, the value of Th maybe relevant to the service type of device B. For example, for aperiodically transmitted service, since the similar interference mayemerge repeatedly in multiple periods, a relatively small Th may beadopted to avoid collision as much as possible. For an event-triggeredservice, since the interference is a one-time event or does not last fora long time, a relatively large Th may be adopted. Or, the value of Thmay be relevant to the transmission power of device B. The higher thetransmission power, the higher the interference to the other device.Through configuring a relatively small Th, the collision may be reduced.

Alternatively, the value of Th may be determined based on a combinationof one or more the above parameters of device A and one or more of theabove parameters of device B. For example, the threshold for thereceived power reference value of device B may be determined accordingto a relationship between the service priorities of device A and deviceB. Or, the threshold for the received power reference value of device Bmay be determined according to a combination of the service types ofdevice A and device B. Or, the threshold for the received powerreference value of device B may be determined according to a combinationof the moving speed of device A and the relationship between the servicepriorities of device A and device B.

For device B, assume that device B needs to occupy resource Y aftersubframe n, Y may include one or more continuous subbands, and thereceived power reference value P_(RSRP) ^(PSSCH) on resource Y exceedsthe corresponding threshold Th. Candidate resources of the selectionwindow may be processed according to the resource Y. Suppose thatR_(x,y) denotes a single subframe resource in selection window [n+T₁,n+T₂], i.e., R_(x,y) is located in subframe y and includes one or morecontinuous subbands starting from subband x. Hereinafter, the methodthat device A determines whether R_(x,y) needs to be excluded isdescribed. Herein, suppose that the resource reservation periodicitythat device A performs resource selection/re-selection is P_(A).

In a first resource exclusion method, if the PRBs of R_(x,y+j·P) _(A)and the PRBs of the resource Y completely overlap or partially overlap,R_(x,y) is unusable for device A, wherein j is an integer larger than orequal to 0, or j is an integer larger than or equal to 0 and is smallerthan C, C is the number of periods that device A needs to reserveresources according to the periodicity P_(A). According to this method,either both the candidate resources 1202 and 1203 in the selectionwindow as shown in FIG. 12 are unusable for device A, or both of themare usable for device A. If both resources 1202 and 1203 are usable,device A may randomly select one resource from resources 1202 and 1203and other candidate resources. As such, interference characteristicdifference between resources 1202 and 1203 and resource Y cannot bereflected, which may lead to decrease of system performance. Inparticular, since resource 1203 has less overlapped part with resourceY, the interference is lower. Thus, device A may select resource 1203preferably.

In a second resource exclusion method, if the PRBs of R_(x,y+j·P) _(A)and the PRBs of resource Y completely overlap or partially overlap, thereceived power reference value P_(RSRP) ^(PSSCH) of the resource Y maybe processed, denoted by P_(RSRP) ^(PSSCH,(e)), and it is determinedwhether R_(x,y) is usable for device A according to P_(RSRP)^(PSSCH,(e)). In other words, if P_(RSRP) ^(PSSCH,(e)) exceeds the abovethreshold Th, R_(x,y) is unusable for device A, wherein j is an integerlarger than or equal to 0, or, j is an integer lager than or equal to 0and is smaller than C, C is the number of periods that devices A needsto reserve resources according to the periodicity P_(A). Assume that thenumber of subbands of R_(x,y+j·P) _(A) , the number of overlappedsubbands between 111 and resource Y is L, i.e., the transmission ofdevice A on the N subbands of R_(x,y+j·P) _(A) merely interfere with theresource Y on L subbands. The interference is decreased. Therefore,P_(RSRP) ^(PSSCH,(e))=f(P_(RSRP) ^(PSSCH), L, N). For example, P_(RSRP)^(PSSCH,(e))=P_(RSRP) ^(PSSCH)·L/N. Or, assume the number of PRBs ofR_(x,y+j·P) _(A) is N′, the number of overlapped PRBs betweenR_(x,y+j·P) _(A) and resource Y is L′, i.e., the transmission of deviceA on the N′ PRBs of resource R_(x,y+j·P) _(A) merely interfere with theresource Y on L′ PRBs. The interference is decreased. Therefore, e.g.,P_(RSRP) ^(PSSCH,(e))=f(P_(RSRP) ^(PSSCH), L′, N′), e.g., P_(RSRP)^(PSSCH,(e))=P_(RSRP) ^(PSSCH)·L′/N′. Hereinafter, the subband is takenas an example to describe the method. The method is also applicable whenPRB is taken as a unit.

According to the second resource exclusion method, if the subbands ofR_(x,y+jP) _(A) is a subset of the subbands of resource Y, e.g., thecandidate resource 1201 in the selection window as shown in FIG. 12,there is further a situation that the subbands of R_(x,y+jP) _(A) ,completely overlap with the subbands of resource Y, e.g., the candidateresource 1202 in the selection window as shown in FIG. 12, P_(RSRP)^(PSSCH,(e))=P_(RSRP) ^(PSSCH), to provide a complete protection to theresource Y to avoid collision. Otherwise, since the transmission ofdevice A on N subbands of R_(x,y+jP) _(A) merely has interference to theresource Y on L subbands, i.e., merely a part of the transmission powerof device A may impact the transmission on resource Y, e.g., thecandidate resource 1203 in the selection window as shown in FIG. 12.Through configuring P_(RSRP) ^(PSSCH,(e))=f(P_(RSRP) ^(PSSCH), L, N), itis avoided that the resource R_(x,y) is excluded too conservatively. Forresource 1203, P_(RSRP) ^(PSSCH,(e))=P_(RSRP) ^(PSSCH)=L/N=P_(RSRP)^(PSSCH)/2, i.e., P_(RSRP) ^(PSSCH,(e)) is decreased by 3 dB compared toP_(RSRP) ^(PSSCH). According to 3GPP specifications, after the resourceis excluded according to the received power, if the ratio of the numberof remained candidate resources and the total number of resources issmaller than R, e.g., R=20%, device A increases the above threshold Thby 3 dB, and performs the resource exclusion again. Herein, the increaseof the threshold Th is performed by a step of 3 dB. According to theabove method, the P_(RSRP) ^(PSSCH,(e)) of resource 1203 is lower thanP_(RSRP) ^(PSSCH) by 3 dB, the partially overlapped resource 1203 iseasier to become usable resource than the completely overlapped resource1202. As such, device A has a higher probability to select resource 1203than resource 1202, which helps to reduce interference between devices.

Embodiment 2

According to the method of embodiment 1, a device A senses an SA ofanother device in the sensing window. According to a correctly receivedSA, if the resources allocated by the SA are not released after subframen, device A may obtain the resource occupation situation of the otherdevice after subframe n. Herein, if device A does not sense one or moreSAs of device B, device A may still be able to determine the resourceoccupation situation of device B after subframe n according to other SAsof device B. Herein, according to the SA successfully received by deviceA in the sensing window, for one subframe/subband after subframe n,there may be one or more other devices need to transmit data on thesubframe/subband.

For one subframe/subband, assume that there are K other devices need totransmit data in the subframe/subband, K is larger than or equal to 1.Device A may respectively obtain K received power reference values ofthe K other devices according to receiving operations in the sensingwindow. In the method of embodiment 1, if the received power referencevalue of at least one UE exceeds the corresponding threshold Th, thesubframe/subband is unusable for device A. In addition, there may be asituation that, the received power reference values of the K devices areall smaller than their corresponding threshold Th. According to themethod of embodiment 1, the subframe/subband is usable for device A. Infact, since device A has sensed that there are multiple devicestransmitting data simultaneously on the subframe/subband, although thereceived power reference value of each device is lower than thethreshold, the subframe/subband may already have a high load. Therefore,embodiments of the present disclosure provide that device A maydetermine whether to occupy the subframe/subband according to acombination of the received power reference values of the K devices.

In a first method for determining whether to occupy thesubframe/subband: device A obtains a sum of the received power referencevalues of the K other devices, and compares the sum of the receivedpower reference values with a threshold Th2. If the sum is larger thanTh2, the subframe/subband is unusable for device A. The threshold Th2may be pre-defined or configured by higher layer. Similarly asembodiment 1, the threshold Th2 may be common for different devices; orthe threshold Th2 may be determined according to one or more parametersof device A, including moving speed, service priority, service type, andtransmission power, etc.; or, for one other device, the threshold Th2may be determined according to one or more parameters of the otherdevice, including moving speed, service priority, service type andtransmission power, etc.; or, the threshold Th2 may be determinedaccording to a combination of one or more parameters of device A and oneor more parameters of the other device. The threshold Th2 may be thesame as the threshold Th determined in embodiment 1. For example, thethreshold Th is common for all of the other devices or is determinedaccording to parameters of device A, thus Th2 may be equal to Th. Or,the threshold Th2 may be different from the threshold Th, e.g.,Th2=Th+Δ, wherein Δ is a predefined constant, or a value configured byhigher layer or determined via other methods. Or, according to themethod of embodiment 1, the thresholds Th of the K devices may bedifferent, and Th2 may be determined according to a minimum value amongthe thresholds Th of the K devices, so as to avoid simultaneoustransmission in one subframe/subband as much as possible. Or, it may bedetermined according to a maximum value among the thresholds Th of the Kdevices, so as to provide more available resources forselection/re-selection. Or, it may be determined according to an averagevalue of the thresholds Th of the K devices. As to the situation thatthe thresholds Th of the K devices are different, besides determining athreshold Th2′ according to the above method, an offset Δ may be furtherintroduced, i.e., Th2=Th2′+Δ, wherein Δ is a predefined constant, or avalue configured by higher layer or determined via other methods.

In a second method for determining whether to occupy thesubframe/subband, device A divides the K devices into groups, andobtains a sum of received power reference values of each group ofdevices, and compares the sum with a corresponding threshold Th3. If thesum of received power reference values of at least one group exceedsTh3, the subframe/subband is unusable for device A. The groups may bedivided according to one or more parameters of the K devices, e.g.,moving speed, service priority, service type and transmission power,etc. For example, devices with the same service priority are dividedinto one group. The group division may be exclusive, i.e., each of the Kdevices belongs to merely one group. Or, each of the K devices may beallowed to be grouped into one or more groups. For example, all deviceswith high service priorities are put in one group, and a threshold Th3is configured according to the high service priority. At the same time,all of the K devices may be put into another group, and a threshold Th3may be configured according to a low service priority. The threshold Th3may be predefined or configured by higher layer Similarly as embodiment1, the threshold Th3 may be common for all devices, or may be determinedaccording to one or more parameters of device A, including moving speed,service priority, service type and transmission power, etc. Or, for agroup of devices of the K devices, the threshold Th3 may be determinedaccording to one or more parameters of the group of devices, e.g.,moving speed, service priority, service type and transmission power,etc. Or, the threshold Th3 may be determined according to a combinationof one or more parameters of device A and one or more parameters of thegroup of devices. The threshold Th3 may be the same as the threshold Thdetermined in embodiment 1. For example, the threshold Th is common forall devices, or is determined based on parameters of device A. Thus,threshold Th3 may equal to Th. Or, threshold Th3 may be different fromthe threshold Th, e.g., Th3=Th+Δ, wherein Δ is a predefined constant ora value configured by higher layer. Or, according to the method ofembodiment 1, assume that the thresholds Th of the devices in one groupare different, Th3 may be determined according to a minimum value amongthe thresholds Th of the group of devices, so as to avoid simultaneoustransmission in one subframe/subband as much as possible. Or, it may bedetermined according to a maximum value among the thresholds Th of thegroup of devices, so as to provide more resources available forselection/re-selection. Or, it may be determined according to an averagevalue of the thresholds Th of the group of devices. For the situationthat the thresholds Th of the group of devices are different, besidesdetermining a threshold Th3′ according to the above method, an offset Δmay be further introduced, i.e., Th3=Th3′+Δ, wherein Δ is a predefinedconstant, or a value configured by higher layer or determined via othermethods.

In a third method for determining whether to occupy thesubframe/subband, a threshold Th is independently determined for each ofthe K devices. For example, the method of embodiment 1 may be adopted.Then, the devices are divided into groups according to their thresholds,i.e. devices with the same threshold are divided into the same group,or, devices with Th within a certain range are put into the same group.Then, a sum of received power reference values of each group of devicesis obtained and compared with a corresponding threshold Th4. If the sumof received power reference values of at least one group exceeds Th4,the subframe/subband is unusable for device A. The threshold Th4 of agroup of devices may be the same as the threshold Th determinedindependently for the group of devices; or, the threshold Th4 of a groupof devices may be different from the threshold Th determinedindependently for the group of devices, e.g., Th4=Th+A wherein Δ is apredefined constant, or a value configured by higher layer or via othermethods. If devices with Th within a certain range are put into onegroup, Th4 may be determined according to a minimum value among thethresholds Th of the group of devices, so as to avoid simultaneoustransmission in one subframe/subband as much as possible. Or, Th4 may bedetermined according to a maximum value among the thresholds Th of thegroup of devices, so as to provide more resources available forselection/re-selection. Or, Th4 may be determined according to anaverage of the thresholds Th of the group of devices. If the deviceswith Th within a certain range are put into one group, besidesdetermining a threshold Th4′ according to the above method, an offset Δmay be further introduced, i.e., Th4=Th4′+Δ wherein Δ is a predefinedconstant, or a value configured by higher layer or via other methods.

In the above three methods for determining whether to occupy thesubframe/subband, device A may obtain the sum of received powerreference values of the devices or devices of a group corresponding tosome SAs that device A correctly receives, and performs the aboveprocessing. In particular, since SA usually has a low coding rate and/orhigh transmission power, device A may have a high probability tocorrectly receive the SA. In some cases, there may be a device whose SAcan be decoded correctly but the received power of the data channelscheduled by the SA is very low. At this time, device A may not considerthe impact of this device when performing the resourceselection/re-selection. As such, a threshold Th5 may be configured. Fora correctly decoded SA, if the received power reference value of thedevice transmitting this SA is lower than Th5, the impact of this deviceis ignored. For any device whose SA is correctly received, if itsreceived power reference value is higher than Th5, the method proceedswith the method of embodiment 1 or one of the three methods fordetermining whether to occupy the subframe/subband in this embodiment,so as to determine whether a corresponding subframe/subband is usablefor device A. Herein, since the resource occupation of some devices withlow transmission power reference values have been ignored, the number ofdevices that device A needs to consider when determining whether asubframe/subband after subframe n is usable is reduced.

The threshold Th5 may be predefined or configured by higher layer.Similarly as embodiment 1, the threshold Th5 may be common for alldevices, or may be determined according to one or more parameters ofdevice A, e.g., moving speed, service priority, service type andtransmission power, etc.; or for a device B, it may be determinedaccording to one or more parameters of the device B, e.g., moving speed,service priority, service type and transmission power, etc.; or, it maybe determined according to a combination of one or more parameters ofdevice A and one or more parameters of device B. The threshold Th5 maybe different from or the same as the threshold Th determined inembodiment 1. The threshold Th5 may be different from or the same as thethresholds Th2, Th3 or Th4.

According to the method of ignoring the resource occupation of somedevices with low received power reference values according to thethreshold Th5, when it is required to determine the available resourcesafter subframe n, the method of embodiment 1 may be adopted, i.e., for asubframe/subband after subframe n, if the received power reference valueof at least one device is higher than the corresponding threshold, thesubframe/subband is unusable for device A. Or, assume that in asubframe/subband after subframe n, there are K′ other devices need totransmit data on this subframe/subband, and the received power referencevalues of them are higher than their corresponding thresholds Th5,wherein K′ is larger than or equal to 1. The above three methods fordetermining whether to occupy the subframe/subband may be adopted. As tothe first method for determining whether to occupy the subframe/subband,device A obtains a sum of the received power reference values of the K′devices, and compares the sum of the received power reference valueswith threshold Th2. If the sum is larger than Th2, the subframe/subbandis unusable for device A. Or, according to the second method fordetermining whether to occupy the subframe/subband, device A divides theK′ devices into groups, and obtains a sum of the received powerreference values of each group of devices, and compares the sum withthreshold Th3. If the sum of at least one group is higher than Th3, thesubframe/subband is unusable for device A. Or, according to the thirdmethod for determining whether to occupy the subframe/subband, device Adivides the K′ devices into groups, obtains a sum of the received powerreference values of each group, and compares the sum with Th4. If thesum of at least one group is higher than Th4, the subframe/subband isunusable for device A.

Embodiment 3

According to the method as shown in FIG. 4, there may be two kinds ofinformation for assisting device A to perform the resourceselection/re-selection in subframe n. One is a method of processing theresource occupation of other devices after subframe n according to SAsensing, i.e. according to the SA of other device B correctly receivedin the sensing window, measure the received power of device B accordingto the scheduling information of the SA to obtain the received powerreference value of the other device after subframe n, so as to assistthe resource selection/re-selection. Another is a method of processingthe resource occupation of other devices after subframe n according tothe total received energy on each subframe/subband in the sensingwindow, i.e., device A obtains the total received energy reference valueof one subframe/subband after subframe n based on the total referenceenergy measurement value in the sensing window according to known orconfigured resource occupation periodicity information, so as to assistthe resource selection/re-selection. In particular, for asubframe/subband after subframe n, device A may determine acorresponding subframe/subband in the sensing window according to someknown or configured resource occupation periodicity information, i.e.,according to the above known or configured periodicity, assume that adevice occupies channel in the corresponding subframe/subband in thesensing window, thus the device will also occupy the subframe/subbandafter subframe n. Therefore, it is possible to determine the totalreceived energy reference value of a subframe/subband after subframe naccording to the total received energy measurement value of thecorresponding subframe/subband in the sensing window, so as to determinewhether device A can use the subframe/subband. Herein, for the subframesoccupied by device A in the sensing window, the impact of the subframesin the sensing window occupied by device A may be not considered whencalculating the total received energy reference value. Or, for thesubframes in the sensing window occupied by device A, the impact ofthese subframes may be processed firstly, i.e., determine some subframesafter subframe n to be unusable for device A, then for other subframesafter subframe n, the impact of the subframes in the sensing windowoccupied by device A may be not considered when calculating the totalreceived energy reference value. Or, if the correspondingsubframe/subband in the sensing window is the subframe occupied bydevice A in the sensing window, device A cannot use a subframe/subbandafter subframe n. Or, if the corresponding subframe/subband in thesensing window is the subframe occupied by device A in the sensingwindow, suppose that the subframe is m, a minimum periodicity is P0, theinterval between the subframe m and the end position of the sensingwindow is M=└(n−b−m)/P₀┘ minimum periodicities, merely when it isdetermined that the periodicity for the corresponding subframe/subbandin the sensing window is larger than M×P₀, device A cannot use thesubframe/subband after subframe n.

For a periodically transmitted service, a device may occupy resourceswith a periodicity P and occupy resources of K subframes in one period.For example, the K resources may be used for repeatedly transmitting thesame data, so as to avoid that other devices cannot receive the data dueto the half-duplex mode. In other words, K resources are allocated tothe device, and each resource is allocated periodically with aperiodicity P. In addition, if the device has occupied the resources fora certain number of periods, the resources should be released, so as toavoid that adjacent devices continuously use the same resources. Fordevice A, after correctly receiving the SA of another device, device Ais able to determine the subframe/subband occupied by the data channelscheduled by the SA and determine whether the subframe/subband willstill be occupied in the following one or more periods according to theinformation carried by the SA. For example, the SA may indicate whetherthe resource will still be occupied in at least the next period; or theSA may indicate whether the current resources will still be occupied inthe following X periods, wherein X is a predefined constant, or a valueconfigured by higher layer or indicated dynamically. In addition, sincea device releases resources after occupying the resource for a certainnumber of periods, device A may use this feature to assist thedetermination of resource occupation of other devices. For example,assume that the SA does not indicate the accurate time that the resourcewill be released. Device A may record the number of times that theresources have been continuously occupied. If the number reachesP_(max), device A may regard that device B has released the resources.

As to an event-triggered service, the transmission may be a one-timeevent. It is still possible to occupy K resources to repeatedly transmitone data, so as to avoid that other devices cannot receive the servicedue to the half-duplex mode. However, at this time, the K resources neednot be occupied repeatedly following a certain periodicity, i.e. for anevent-triggered service, the resources are released after being occupiedfor one time.

For a periodically transmitted service, through receiving the SA, thedevice A may sense in the sensing window that resources are occupied bydevice R in C1 continuous periods, and these resources are released inthe sensing window. As shown in FIG. 7, in the sensing window, thedevice R occupies one resource in three periods (701˜703). However, inthe last four periods (711-715) before the sensing window ends, device Rhas re-selected another resource and occupies the resource until aftersubframe n. For an event-triggered service, the resources occupied bydevice R in the sensing window are also released. It is required todesign the resource processing mechanism, such that the resources whichhave been released do not impact the resource selection/re-selection ofdevice A after subframe n.

On one hand, for the periodically transmitted service, in the method ofprocessing the resource occupation of other devices after subframe nbased on SA sensing and received power reference value, as to thereleased resources of another device R, device A does not need toconsider the occupation of such resources of device R after subframe n.On the other hand, as to the method of processing the resourceoccupation of other devices after subframe n based on the total receivedenergy of each subframe/subband in the sensing window, for theperiodically transmitted service and the event-triggered service, sincethe resource occupied by device R has been released, the impact of thereceived power of the released resources should be eliminated whendetermining the total received energy reference value of eachsubframe/subband after subframe n. In the sensing window, for onesubframe/subband occupied by device R, assume the received powermeasurement value of device R is P_(R), and the total received energy ofthe corresponding subframe/subband is E. After the impact of thereleased resources occupied by device R is eliminated, the effectivetotal received energy of the subframe/subband is E′=E−P_(R). Theeffective total received energy E′ may be used for determining the totalreceived energy reference value after subframe n.

In the sensing window, through receiving the SA, device A may sense theresource occupation of another device B, and may sense that the resourceis still not released at the end of the sensing window. As this time,the impact of device B needs to be considered after subframe n.

As to the method of processing the resource occupation of other devicesafter subframe n based on the total received energy of eachsubframe/subband in the sensing window, for a subframe/subband aftersubframe n, device A may determine a corresponding subframe/subband inthe sensing window according to some known or configured resourceoccupation periodicity information, and determine whether device A canuse the subframe/subband after subframe n according to the totalreceived energy measurement value of this correspondingsubframe/subband. The devices except for device A may be classified intothree types. The first type device transmits data on the correspondingsubframe/subband in the sensing window and continues to occupy thesubframe/subband after subframe n following the periodicity of the firsttype device. The second type device transmits data on the correspondingsubframe/subband in the sensing window, but according to theperiodicity, the second type device does not occupy the subframe/subbandafter subframe n. The third type device does not transmit data on thecorresponding subframe/subband in the sensing window. However, accordingto the periodicity of the third type device, it occupies thesubframe/subband after subframe n.

For the above first type device, the total received energy measured onthe corresponding subframe/subband in the sensing window has alreadyinclude the impact of the first type device, no additional adjustment isrequired.

For the above second type device, the total received energy measured onthe corresponding subframe/subband in the sensing window additionallyinclude the impact of the transmission of the second type device. But infact the second type device does not need to transmit data on thesubframe/subband after subframe n, therefore the received power of thesecond type device needs to be removed from the total received energymeasured on the corresponding subframe/subband. Or, the impact of thereceived power of the second type device may also be removed from thetotal received energy reference value of the subframe/subband aftersubframe n. As shown in FIG. 8, in order to obtain the total receivedenergy reference value on resources 807 and 808 after subframe n, assumethat the impact to the total receiving measurement value on resources801˜806 is considered with a periodicity of 200 ms. For device 1, itsresource 812 overlaps with resource 805, i.e., the total received energymeasurement value of resources 812/805 includes signal energy ofdevice 1. However, since the SA of device 1 indicates that itsperiodicity is 500 ms, device 1 does not occupy resources 807 and 808after subframe n. Therefore, the impact of the received power of device1 needs to be eliminated from the total received energy of resources812/805, so as to obtain an effective total received energy of resources812/805. The above effective total received energy and the totalreceived energy of resources 801˜804/806 are used for determining thetotal received energy reference value of resources 807 and 808. Assumethat the total received energy measurement value of the correspondingsubframe/subband in the sensing window is E, the received powermeasurement value of the second type device B is P_(B). Thus, theeffective total received energy of the subframe/subband may be correctedto E′=E−P_(B), so as to obtain a more accurate total received energyreference value according to the effective total received energymeasurement value. Alternatively, it is also possible to calculate thetotal received energy reference value of resources 807 and 808 accordingto the total received energy measurement value of resources 801˜806, andthen eliminate the impact of the received power of device 1, so as toobtain the total effective energy reference value for determiningwhether resources 807 and 808 are usable.

For the third type device, the total received energy measurement valueobtained on the corresponding subframe/subband in the sensing windowdoes not consider the impact of the transmission of device B. However;the third type device in fact needs to transmit data on thesubframe/subband after subframe n. Therefore, the received power of thethird type device needs to be included in the total received energymeasured on the corresponding subframe/subband. Alternatively, it isalso possible to include the received power of the third type device inthe total received energy reference value of the subframe/subband aftersubframe n. As shown in FIG. 9, in order to obtain the total receivedenergy reference value of resource 907 after subframe n, assume that theimpact to the total received energy measurement value on resources901˜906 is considered with a periodicity of 200 ms. Herein, since the SAof device 1 indicates that its periodicity is 500 ms, merely theresource 911 of device 1 overlaps the above resource 902, i.e., thetotal received energy measurement value has already included the signalenergy of device 1. However, for resources 901, 903˜906, the totalreceived energy measurement value does not include the signal energy ofdevice 1. Therefore, the impact of device 1 needs to be incorporatedinto the total received energy measurement value of resources 901,903˜906, so as to obtain the effective total received energy ofresources 901, 903˜906. The effective total received energy and thetotal received energy of resource 902 are used for determining the totalreceived energy reference value of resource 907. Assume that the totalreceived energy measurement value of the corresponding subframe/subbandis E, the received power reference value of the third type device B onthe subframe/subband after subframe n is P_(B). Thus, the energy E maybe corrected to obtain the effective received energy E′=E+P_(B) on thesubframe/subband after subframe n. Alternatively, it is also possible tocalculate the total received energy reference value of resources901˜906, and then deal with the impact of device 1 to obtain totalreceived energy reference value used for determining whether resource907 is usable. Alternatively, in FIG. 9, it is also possible toeliminate the received power of device 1 from the total received energyof resource 902, and then a total received energy reference value iscalculated for a combination of resource 902 and the resources 901,903˜906. Then, the impact of device 1 is introduced to obtain the totalreceived energy reference value used for determining whether resource907 is usable. If the received power reference value of resourceoccupied by the third type device B is relatively small, if merely theimpact of the third type device B is considered, it will not make thecorresponding resource unusable for device A. However, since thetransmission of the third type device B is periodical, the resourceoccupation of the third type device B may lead to increase of the totalreceived energy on one subframe/subband after subframe n. When itexceeds a threshold, the subframe/subband is unusable for device A.

As to the method of processing the resource occupation of other devicesafter subframe n according to the total received energy on eachsubframe/subband in the sensing window, device A may determine the totalreceived energy reference value of one subframe/subband after subframe naccording to one or more periodicities based on some known or configuredresource occupation periodicity information.

As to a subband y of subframe x after subframe n, if multipletransmission periods of an interfering device need to be considered, atotal received energy reference value may be respectively determined foreach interfered period needs to be considered, so as to determinewhether subband y of subframe x is usable for device A according to themultiple total received energy reference values. For example, a maximumvalue of the multiple total received energy reference values may betaken as the total received energy reference value of thesubframe/subband, so as to determine whether the subframe/subband isusable for device A. Subsequently, the total received energy referencevalue of the subframe/subband may be compared with a threshold Th6. Ifit exceeds the threshold Th6, device A cannot occupy thesubframe/subband.

As to a subband y in subframe x after subframe n, assume that onetransmission period P of an interfering device needs to be considered.When determining the total received energy reference value, the impactof subband y in subframes x−m·P in the sensing window needs to beconsidered, wherein m is an integer which makes x−m·P located in thesensing window. The set of subframes need to be considered is denoted byM. The total received energy reference value may merely consider thelast subframe in set M, i.e. the impact of the total received energy ofsubband y in the subframe closest to the end of the sensing window inthe set M. For example, the total received energy reference value equalsto the effective total received energy E′ of subband y in the lastsubframe of the set M. Or, the total received energy reference valueequals to E′+Δ, wherein. Δ is an offset. Or, the total received energyreference value may consider the impact of some or all subframes in theset M, e.g., the total received energy reference value may be an averagevalue, a weighted average value or a moving average value of theeffective total received energy of the subframes.

In the above method, the threshold Th6 may be a predefined value or avalue configured by higher layer. Or, the threshold Th6 may depend onone or more parameters of device A. For example, Th6 may be relevant tothe moving speed of device A, e.g., the higher the moving speed, thefaster the received power varies, and a relatively small Th6 may beadopted to avoid potential collision as much as possible. Or, Th6 may berelevant to the service priority of device A, e.g., for a service with ahigh priority, in order to obtain more usable resources to ensure thetransmission performance of the higher priority service of device A, arelatively large Th6 may be adopted. Or, in order to reduce collision,it is also possible to adopt a relatively small Th6. Or, Th6 may berelevant to the service type of device A, e.g. for a periodicallytransmitted service, since the interference may emerge repeatedly inmultiple periods, a relatively small Th6 may be adopted to avoidcollision as much as possible; whereas for an event-triggered service,since the interference is a one-time event or not last for a long time,a relatively large Th6 may be adopted. Or, Th6 may be relevant to thetransmission power of device A, the higher the transmission power, thelarger the interference to the other devices. A relatively small Th6 maybe configured to reduce the collision.

Embodiment 4

As to the problem in embodiment 3, for the method of processing theresource occupation of other devices after subframe n based on the totalreceived energy of each subframe/subband in the sensing window, afollowing method may be adopted.

For a subframe/subband in the sensing window, the signals of the datachannels scheduled by all correctly received SAs may be removed, so asto measure the total received energy of merely the remaining signals onthe subframe/subband. Or, it is also possible to remove the signals ofthe data channel scheduled by the correctly received SA only when thereceived power of the data channel scheduled by the SA exceeds athreshold, and then measure the total received energy of the remainingsignals on the subframe/subband. For example, for a subframe/subband,assume the total received energy measurement value is E, the receivedpower measurement value of the data channel scheduled by an SA is P_(S),and the sum of received power measurement values of all data channels tobe removed on the subframe/subband is ΣP_(S), then after the signals ofthe data channels scheduled by the correctly received SA are removed,the total received energy of the remaining signals is E_(R)=E−ΣP_(S).

For a subframe/subband after subframe n, device A may determine acorresponding subframe/subband in the sensing window according to someknown or configured resource occupation periodicity information, i.e.,according to the known or configured periodicity, assume a deviceoccupies a channel on a corresponding subframe/subband in the sensingwindow, the device will also occupy a subframe/subband after subframe n.As such, it is possible to determine the total received energy referencevalue E_(R,ref) of the remaining signals on the subframe/subband aftersubframe n according to the total received energy measurement value ofthe remaining signals on the corresponding subframe/subband.

For a subband y in subframe x after subframe n, if a transmission periodP of the interfering device is considered, when determining the totalreceived energy reference value of the remaining signals, the impact ofsubband y in subframes x−m·P in the sensing window needs to beconsidered, wherein m is an integer which makes x−m·P located in thesensing window. Assume that the set of subframes need to be consideredis M. The total received energy reference value of the remaining signalsmay consider the impact of merely the last subframe in the set M, i.e.,the subband y in the subframe closest to the end of the sensing window.For example, the total received energy reference value of the remainingsignals equals to the total received energy E_(R) of the remainingsignals of subband y in the last subframe x−m·P of the set M, or thetotal received energy reference value of the remaining signals equals toE_(R)+Δ, wherein Δ is an offset. Or, the total received energy referencevalue of the remaining signals equals to an average value, a weightedaverage value or a moving average value of the total receiving energiesE_(R) of the remaining signals of the subframes.

For a subband in a subframe after subframe n, if multiple transmissionperiods of the interfering device are considered, a total receivedenergy reference value of the remaining signals may be respectivelydetermined for each interfered period needs to be considered, and thenthe total received energy reference value E_(R,ref) of the remainingsignals of the subframe/subband is obtained. For example, the maximumvalue of the total received energy reference values of the remainingsignals may be taken as the total received energy reference valueE_(R,ref) of the remaining signals on the subframe/subband.

Alternatively, for a subframe/subband after subframe n, the totalreceived energy reference value E_(R,ref) of the remaining signals ofthe subframe/subband may be obtained according to the total receivedenergy measurement value of the remaining signals of the same subband inall subframes in the sensing window. For example, E_(R,ref) may be anaverage value, a weighted average value or a moving average value of thetotal receiving energies E_(R) of the remaining signals of allsubframes. According to this calculation method, although the predictionof the remaining signal strength after subframe n merely reflects anaverage effect of the measurement of the sensing window, since theperiodicity information of the remaining signals and whether theresources are released are unknown, the average operation is able toreflect characteristic of the remaining signals to some extent.

In fact, in the sensing window, through receiving the SA, device A maysense the resource occupation from one or more devices and the resourcesare not released. Therefore, the impact of the one or more devices needsto be considered after subframe n. If the received power reference valueof the one or more devices is relatively small, it may not make thecorresponding resources unusable for device A. However, due to theresource occupation of the one or more devices, the total receivedenergy on a subframe/subband after subframe n may be increased. When itexceeds a threshold, the subframe/subband becomes unusable for device A.Thus, for a subframe/subband after subframe n, based on the totalreceived energy reference value of the remaining signals and consideringthe received power reference values of other devices need to occupy thesubframe/subband obtained via receiving the SA, the total receivedenergy reference value of the subframe/subband can be obtained.

In particular, for a subframe/subband after subframe n, assume thatdevice A determines according to the received SA that a devicetransmitting the SA needs to occupy channel in the subframe/subband, andthe received power reference value of the device transmitting the SA isPPPB. Thus, in this subframe/subband, the total received energyreference value of all possible signals is E_(ref)=E_(R,ref)+ΣP_(B),wherein ΣP_(B) denotes a sum of the received power reference values ofdevices need to occupy channel in the subframe/subband. Then, the totalreceived energy reference value—may be compared with the threshold Th6.If E_(ref) exceeds the threshold Th6, device A cannot use thissubframe/subband.

As shown in FIG. 10, on one hand, in the sensing window, all datasignals (1001˜1006, 1011˜1012 and 1021˜1022) of devices sensed via SA inthe sensing window are removed and the total received energy of theremaining signals is measured, to obtain the total received energyreference value 1 of the remaining signals on the resource 1007/1023after subframe n and the total received energy reference value 2 of theremaining signals on resource 1008 after subframe n. On the other hand,since the SAs of devices 1-3 are received, and devices 1 and 3 need tocontinue to occupy resources 1007/1023, and merely device 3 needs tocontinue to occupy resource 1008, the received power reference values ofdevices 1 and 3 are further added to the total received energy referencevalue 1 of the remaining signals, so as to obtain the total receivedenergy reference value on resources 1007/1023 after subframe n. If thetotal received energy reference value of the remaining signals exceedsthe threshold, resource 1007/1023 is unusable after subframe n. Thereceived power reference value of device 3 may be further added to thetotal received energy reference value 2 of the remaining signals, so asto obtain the total received energy reference value of resource 1008after subframe n. If the total received energy reference value exceedsthe threshold, the resource 1008 is unusable after subframe n.

In accordance with the above method, embodiments of the presentdisclosure also provide an apparatus. The apparatus may be used forimplementing the above method. As shown in FIG. 11, the apparatusincludes a sensing module, a resource selecting module and atransmitting/receiving module; wherein

the sensing module is to sense an SA from another device, measure areceived power of the SA and measure energy of each subband in aresource pool;

the resource selecting module is to select or re-select resources for anSA and a data channel of the apparatus according to the sensed SA of theother device, resources occupied by the other device indicated by theSA, the received power of the SA and the energy of each subband in theresource pool; and

the transmitting/receiving module is to receive the SA and a datachannel from the other device, and transmit the SA and the data channelof the apparatus according to the selected/re-selected resources.

Those with ordinary skill in the art may understand that some or allsteps for implementing the above method may be implemented via programexecuted by relevant hardware. The program may be stored in a computerreadable storage medium. When the program is executed, one or more stepsof the above method are implemented.

In addition, the functional modules in various embodiments of thepresent disclosure may be integrated into one processing module, or maybe independent physical modules. Or, two or more modules may beintegrated into one module. The integrated modules may be implementedvia hardware, or implemented as software functional modules. When beingimplemented as software functional modules and sold or used as anindependent product, the integrated modules may be stored in a computerreadable storage medium.

The above-mentioned storage medium may be read only memory, disk orcompact disk, etc.

The foregoing are only preferred embodiments of the present inventionand are not for use in limiting the protection scope of the presentinvention. Any modification, equivalent replacement and improvement madewithin the scope of the present invention should be covered under theprotection scope of the present invention.

What is claimed is:
 1. A method for transmitting data by a first device,the method comprising: receiving, from a second device, sidelinkscheduling information for the second device on a physical sidelinkcontrol channel (PSCCH); determining a resource for sidelinktransmission among a plurality of candidate resources for sidelinktransmission based on the sidelink scheduling information; andtransmitting data on a physical sidelink shared channel (PSSCH) based onthe determined resource, wherein a first candidate resource includingcontinuous subbands in a first time resource is excluded among theplurality of candidate resources for sidelink transmission, in case thatthe first device has not monitored a second time resource and the firsttime resource is determined based on the second time resource and aresource reservation period.
 2. The method of claim 1, furthercomprising: measuring a received power of a demodulation referencesignal (DMRS) for the PSSCH based on the sidelink schedulinginformation, wherein a second candidate resource is excluded among theplurality of candidate resources for sidelink transmission in case thata received power of a DMRS in the second candidate resource is higherthan a threshold.
 3. The method of claim 2, wherein the threshold isdetermined based on a first priority for the first device and a secondpriority for the second device.
 4. The method of claim 1, wherein thefirst time resource and the second time resource satisfy the followingequation:y+j×P _(a) =m+P _(q), and wherein y is the first time resource, j is aninteger larger than or equal to 0, P_(a) is a first resource reservationperiod, m is the second time resource, and P_(q) is a second resourcereservation period.
 5. A first device for data transmission, the firstdevice comprising: a transceiver; and a controller coupled with thetransceiver and configured to control to: receive, from a second device,sidelink scheduling information for the second device on a physicalsidelink control channel (PSCCH), determine a resource for sidelinktransmission among a plurality of candidate resources for sidelinktransmission based on the sidelink scheduling information, and transmitdata on a physical sidelink shared channel (PSSCH) based on thedetermined resource, wherein a first candidate resource includingcontinuous subbands in a first time resource is excluded among theplurality of candidate resources for sidelink transmission, in case thatthe first device has not monitored a second time resource, and the firsttime resource is determined based on the second time resource and aresource reservation period.
 6. The first device of claim 5, wherein thecontroller is configured to: measure a received power of a demodulationreference signal (DMRS) for the PSSCH based on the sidelink schedulinginformation, wherein a second candidate resource is excluded among theplurality of candidate resources for sidelink transmission in case thata received power of a DMRS in the second candidate resource is higherthan a threshold.
 7. The first device of claim 6, wherein the thresholdis determined based on a first priority for the first device and asecond priority for the second device.
 8. The first device of claim 6,wherein the first time resource and the second time resource satisfy thefollowing equation:y+j×P _(a) =m+P _(q), and wherein y is the first time resource, j is aninteger larger than or equal to 0, P_(a) is a first resource reservationperiod, m is the second time resource, and P_(q) is a second resourcereservation period.